Sift together 1-1/2 cups sugar, flour and cocoa; set aside, In a large bowl, beat egg whites, vanilla and chocolate flavoring until foamy, Combine cream of tartar, salt and remaining sugar; add a little at a time to bowl, Beat until very stiff but not dry peaks form, Gradually fold in flour mixture; do not over mix, Pour into an ungreased 10-in,______, Bake at 350° for 45 minutes, Remove from oven and invert pan; allow to cool completely before removing from pan, Serve with ice cream and fudge sauce if desired,